Eyeball
noun
What is an eye ball? Oh wait, that's easy. It's an eyeball!
めだま
This is a jukugo word, which usually means on'yomi readings from the kanji. 目玉, however, is an exception. Perhaps this is because it includes a body part (the eye) in it, which often makes a word switch to kun'yomi readings. Either way, it doesn't matter too much. Both the readings you learned for the kanji in this word are the kun'yomi, meaning you should know how to read this one. Just make sure you watch out for the rendaku.
サーモンは目玉もおいしいですよ。
Salmon eye balls are tasty too.
びっくりして目玉が出るかとおもった。
I was so surprised I thought my eyeballs were going to pop out.
セールの目玉はトマトです。
The highlight of the sale is tomatoes.